The impact of socio-economic development on water production and utilization is substantial and can be seen in several ways [4] : 1) an increase in population and economic growth can lead to higher water demand for household, industrial, and agricultural use; 2) improved living standards and rising incomes can increase water usage for domestic purposes, such as for washing and flushing toilets; 3) expansion of the agricultural and industrial sectors can result in higher water usage for irrigation and industrial processes; 4) changes in consumption patterns, such as an increase in meat consumption, can lead to higher demand for water-intensive food production.

This increase in demand is influenced by factors such as urbanization, industrialization, population growth, and changes in consumer behavior. Additionally, as economies grow, more people can afford to live in single-family homes with lawns, swimming pools, and other amenities that require substantial amounts of water. This heightened demand for water puts stress on the municipal water supply and requires the development of new water sources or the expansion of existing ones.

The strain on municipal water supplies as a result of increased demand is well-documented. The development of new water sources or the expansion of existing ones is often necessary to meet the growing demand [5] . In addition, improved water management practices, such as water-saving technologies, are also needed to ensure sustainable and efficient use of water resources.

In many GCC countries, the industrial sector is one of the users of the municipal water supply network. Industrialization can also has a significant impact on municipal water demand, as it requires large amounts of water for processes such as cooling, cleaning, and chemical production [6] .

The effects of socio-economic development on agriculture water demand can be diverse and multifaceted. On the positive side, a rise in income levels and advancements in technology can result in higher demand for food and agricultural products and more efficient use of water. However, increased urbanization and competition for water from other sectors, such as urban areas, industry, and energy production, can lead to land-use changes, reducing the availability of water for agriculture. It is important to note that the impact of socio-economic development on agriculture water demand will depend on the unique circumstances and the interplay of various factors, including environmental, economic, and political conditions [7] [8] . Moreover, effective water management policies and practices can help mitigate the negative impacts and enhance the positive effects of socio-economic development on agriculture water demand [9] .

The increasing demand for food, driven by population growth, urbanization, dietary changes, and consumption patterns, is further exacerbating food insecurity [10] . Changes in consumer behavior, such as increased meat consumption, can also put pressure on water resources as animal agriculture (fodders) is a water-intensive industry [11] . The Food and Agriculture Organization (FAO) of the United Nations warns that food supply will be under unprecedented stress as the world’s population reaches 10 billion by 2050, and food demand approaches the limits of modern agricultural development [12] .

Food production is both water- and energy-intensive, with agriculture accounting for 70% of global human freshwater consumption and 23% - 48% of energy consumption in agriculture being attributed to irrigation [10] . Energy shortages and water scarcity in food production can limit food output. Moreover, the energy sector faces a supply-demand imbalance, with energy demand projected to increase by 50% in 2030 due to population and economic growth [10] . This means that energy production will not be able to keep pace with demand, leaving about 3 billion people without access to safe and reliable energy. Water scarcity also poses a significant threat to global energy security, as water withdrawal for electricity generation accounts for 88% of that from the energy sector [10] .

The relationship between socio-economic development and energy demand is complex and can vary greatly based on local and global factors. On one hand, higher income levels, economic growth, and urbanization can drive up energy demand as individuals and businesses have greater resources to invest in energy-intensive activities and technologies [13] . On the other hand, advancements in energy efficiency and the growth of renewable energy sources can reduce energy demand by limiting the need for traditional fossil fuels [14] . Additionally, shifts in social and cultural norms, such as a greater focus on sustainability, can lead to decreased energy consumption [15] . Ultimately, the specific impact of socio-economic development on energy demand will depend on the interplay of various factors, including economic, political, and technological conditions, as well as the availability of energy resources.

Warmer temperatures lead to higher water usage. These effects can lead to challenges for municipalities in meeting the water demands of their communities and protecting public health. It can also result in increased water management costs, potentially affecting the overall economy [16] . Using monthly per capita consumption, population and average temperatures for the period 1998-2017 in Kuwait, it is estimated that an increase in temperature of 1˚C, lead to an increase in per capita municipal water consumption by 5.386 l/cap/day [17] .

The impacts of climate change on food production are becoming more severe, as predicted by the Intergovernmental Panel on Climate Change [10] . Climate change impacts on agriculture water demand can be significant, including [12] : 1) increased water demand due to higher temperatures and longer growing seasons; 2) decreased water availability due to droughts and reduced snowpack; 3) intense precipitation leading to runoff and decreased infiltration, making water less accessible for crops; 4) sea-level rise affecting water quality and availability in coastal regions; and 5) shifting precipitation patterns leading to changes in crop water requirements.

These impacts can result in challenges for agriculture, including decreased crop yields, reduced production, and increased costs for irrigation and water management. This, in turn, can impact food security and the economy. Quantitatively speaking, in arid regions, an increase of 1˚C temperature will increase crop water requirement by 2.9% [18] .

The impact of climate change on energy demand can be significant and far-reaching, with important implications for both energy production and consumption. The main effects include [19] : 1) rising demand for cooling, as temperatures rise due to climate change, there is a growing need for air conditioning and cooling systems, leading to increased energy demand; 2) boosting renewable energy, climate change has led to increased interest and investment in renewable energy sources such as solar, wind, and hydro power, as a way to reduce greenhouse gas emissions and limit global warming; 3) changes in consumption patterns, climate change is also leading to changes in patterns of energy consumption, with more use of air conditioning in the summer and heating in the winter, further driving up energy demand; and 4) shift away from fossil fuels, as awareness of the damaging impact of fossil fuels on the environment grows, there is a growing trend towards clean energy sources and away from traditional fossil fuels, further shaping energy demand. Quantitatively speaking, an increase of 2˚C in 2050 will increase the energy demand by 41.5% [20] .

Scenario development aims to create a set of future scenarios that consider future changes of WEF production and use technologies as well as the impacts of climate change and socio-economic development. This step should examine the relationships between the sectors, and how changes in one sector affect the others. For example, increased water availability may lead to increased energy production, but may also lead to reduced food production due to competition for water resources.

This can involve the use of scenario planning techniques to create a range of possible futures, considering expected trends in each sector, potential impacts of climate change, and potential technological advancements or policy changes. A range of future prospects to support the development of effective policies in the WEF nexus is presented in sequence.

The aim of the WEF nexus analysis is to identify and prioritize opportunities to quantify and optimize the use of the water, energy and resources in a balanced and integrated manner, taking into account the trade-offs and synergies between them [2] [38] . The WEF nexus analysis consists of the following two key elements: 1) quantification, which it refers to the measurement and assessment of the availability and demand for water, energy, and food resources. This includes evaluating the resources’ current and future use, and their potential for growth and expansion [22] [39] ; 2) allocation, which it refers to the distribution of resources among different sectors and uses, such as agriculture, industry, households, irrigation, electricity generation, and food production. The aim is to allocate resources in a sustainable and equitable manner, taking into account the interdependence of the water, energy, and food systems [22] [40] .

There are various modeling approaches to model the interconnections between water, energy, and food systems, each having strengths and weaknesses [41] [42] . There are various tools and approaches that can be utilized in WEF nexus analysis, depending on the specific context and objectives of the analysis. In this study, the Q-Nexus method [2] [22] [43] was used. The Q-Nexus method provides a comprehensive framework for simulating the WEF nexus at a systemic level and assessing the interrelationships between water, energy, and food systems. In this model, the water, energy and food sectors are categorized by a set of production technologies. It integrates a Leontief production function, which considers inter-sectoral resource utilization and final demand to determine sector outputs. By applying the Q-Nexus method, we can obtain quantitative results that directly and indirectly demonstrate the interdependence of water, energy, and food systems.

Tables 1-3 illustrate the water, energy and food sector production quantities presented by production process/technology considered in this study.

Table 4 and Table 5 present the collected data of water use in food production for plants and animals, respectively. Table 6 and Table 7 present the collected data of energy use in water production and food production, respectively.

Several WEF-Nexus scenarios were conducted to explore the effects of management interventions in one sector on the other two sectors. These scenarios aimed to assess the future implications of various factors such as WEF demand projections, climate change, and the introduction of renewable energy in Kuwait.

Reference scenario: A baseline was established by creating a reference scenario for the year 2035, taking into account the projected demands of the Water-Energy-Food (WEF) sector. These demands were determined by considering the anticipated population growth and assuming the current rates of water, energy, and food consumption per person. The reference scenario also incorporated the impact of climate change on municipal water demand in 2035, considering the temperature rise under RCP 8.5 [54] , and an estimation that an increase in 1˚C in temperature in Kuwait would result in an increase in per capita municipal water consumption by 5.4 liters/day [17] . Furthermore, the influence of climate change on agricultural water demand in 2035 was factored in, based on the existing agricultural water demands [53] , and the research findings that a 1˚C increase in temperature would result in a 2.9% growth in crop water requirement (CWR) in arid regions [18] . In addition, based on Kuwait’s national plan to have 15% of renewable energy in its energy portfolio, by 2030; this scenario includes replacing 15% of energy produced by steam turbines with renewable energy production technology (Solar Photovoltaic).

Following the establishment of the reference scenario, several management intervention scenarios were compared to it to assess their effectiveness in reducing trade-offs and building synergies among the three sectors. These scenarios focused on changes in demand and technology within the water, food, and energy sectors, as follows:

1) Reduction in per capita water consumption scenario: In the water sector, the first scenario explored a reduction in per capita water consumption, incorporating efficiency measures aligned with the targets of the GCC Unified Water Strategy 2035 [25] .

2) Switching to more efficient desalination technologies scenario: The second water scenario involved transitioning to more efficient desalination technologies, specifically increasing the share of multi-effect desalination technology (MED) from 19.2% in 2018 to 42.2% in 2035 [55] , while decreasing the share of MSF technology from 51.7% to 28.7%, as per the government efforts and plans to enhance the efficiency of energy use in desalination.

3) Improving irrigation efficiency scenario: The food scenarios focused on improving irrigation efficiency to reduce water demand in the agricultural sector. Similar to scenario for the reduction in per capita water consumption, the irrigation efficiency target is aligned with the targets of the GCC Unified water Strategy 2035 [25] .

4) Switching to more efficient fuel for electricity production scenario: Within the energy sector, scenarios explored the adoption of more efficient technologies and a shift from oil to gas as a fuel source for electricity production.

Each of these scenarios was analyzed individually and combined, comparing their impacts on the WEF-nexus with the reference scenario. The reference year for all scenarios was 2018, and the target year considered was 2035, aligning with the objectives of Kuwait Vision 2035.

Table 8 presents the simulation results, showcasing the percentage decrease of various factors/indicators when compared to the reference scenario. These factors/indicators include total water demand, total energy demand, desalinated water production, implementation cost, energy consumption for desalination, and desalination greenhouse gas (GHG) emissions and brine discharge.

The simulation results indicated that business-as-usual scenario (i.e., reference scenario) for the management of the water, energy, and food sectors will be associated with relatively high investment costs and resources shortage risks; yet, there exists major opportunity to reduce these costs and risks, especially in the water sector, where it is found that the reduction in per capita municipal water consumption from 175 m³/year in 2018 to 90 m³/year by 2035 is the most effective scenario in reducing desalination cost and its associated environmental impacts by 45%. In this scenario, desalinated water can be reduced and consequently, desalination energy cost, GHGs emissions, and brine discharge to the marine environment will be also decreased.

Due to the fact that Kuwait depends essentially on imports for its food supply, the impact of the food sector scenarios on the other sectors is found to be very minor.

Finally, the combined scenario, representing the efforts in the three sectors, shows a higher saving in total energy and water demands up to 46%. Consequently, this will lead to a reduction in desalinated water. Therefore, the cost of desalination energy, GHGs emissions, and brine impact will decrease accordingly.

The WEF nexus in Kuwait highlights the importance of balancing the needs of different sectors and ensuring sustainable resource management practices. Addressing the challenges faced by the WEF nexus is crucial for ensuring the long-term sustainability of Kuwait’s resources and for meeting the needs of its growing population. The country has the potential to become a leading example in sustainable resource management, but more efforts are needed to address the challenges faced in the WEF nexus and to ensure long term sustainability.

Since the per capita municipal water consumption in Kuwait is an important influencer on the WEF nexus, particularly in terms of water and energy consumption, it is important to focus on demand management as more effective approach than on supply management and efficiency approaches. In other words, it would be important to look at policies that reduce per capita water consumption in the municipal sector prior to the expansion in desalination plants. To implement demand management strategies in the municipal water sector, there are basically three policy instruments that can be used: 1) structural & operational (e.g., metering, retrofitting water saving devices, flow control, recycling); 2) socio-political (e.g., education and awareness, building codes, appliances labelling); and 3) economic (incentives and disincentives). Experience has shown that combining these policy instruments to achieve the desired consumption changes is considered to be more effective and can complement and reinforce each other. In the case of Kuwait, probably restructuring the current water tariff system, which is currently a flat rate tariff that does not encourage conservation, installing water saving devices, enacting water conservation building codes, and education campaigns are the policy instruments that would be effective in influencing per capita water consumption in the municipal sector.

It is important to revise Kuwait policies related to desalination technologies presently in use. Currently, Kuwait relies on thermal desalination technology and it is highly recommended that a shift towards membrane technology (i.e., RO) is made. This will provide the advantage of less emissions compared to thermal technologies and the ability to use any source of energy such as renewable and nuclear energies.

With regard to the agriculture sector, it is recommended that the government adopts policies to encourage farmers to use modern irrigation technologies, which would lead to greater efficiency in water use. Because the agriculture sector is highly subsidized by the government, the government can enhance the irrigation efficiency by linking subsidies with implementation of water saving irrigation and agricultural systems.

Moreover, it is highly recommended that the current institutional structure in Kuwait is revised to allow for WEF coordination and collaborative planning. A WEF governance structure will need to exist in order to facilitate the interaction between the three sectors and their collaborative planning. This structure need not be a new physical structure, i.e., establishing new institutes, but could be a soft structure, such as a committee that coordinates and allows collaborative planning and management of the three sectors.